JP3825275B2

JP3825275B2 - Electrical contact member and its manufacturing method

Info

Publication number: JP3825275B2
Application number: JP2001115083A
Authority: JP
Inventors: 菊池　　茂; 雅也高橋; 馬場　　昇; 将人小林; 芳友後藤; 安昭鈴木; 隆佐藤
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2001-04-13
Filing date: 2001-04-13
Publication date: 2006-09-27
Anticipated expiration: 2021-04-13
Also published as: KR20020079331A; CN1311492C; US20030010752A1; CN1381857A; EP1249848B1; JP2002313196A; US6765167B2; TW526508B; EP1249848A3; EP1249848A2

Description

【０００１】
【発明の属する技術分野】
本発明は、真空遮断器、真空開閉器等に用いられる新規な電気接点部材及びその製法並びにそれを用いた真空バルブ、真空遮断器に関する。
【０００２】
【従来の技術】
真空遮断器等に設置される真空バルブ内の電極構造は、一対の固定側電極及び可動側電極から成っている。上記固定側及び可動側電極の構造は、電気接点と該電気接点に連なる電極棒からなり、該電気接点の裏面にはしばしばステンレス等の板が補強板として設けられる。
【０００３】
大電流、高電圧遮断用電気接点部材としては、Ｃｒ−Ｃｕの複合金属材料が多く用いられる。
【０００４】
この電気接点の製造方法は、各成分の金属粉末あるいはこれらの混合粉を所定の組成で、例えば円板等の単純形状に成形後、焼結するいわゆる粉末冶金法により製造された電気接点部材を、更に機械加工して所定形状とする。なお、電気接点には発生したアークに駆動力を与えて、アークを一箇所に停滞させずに電極の外周部へ移動させるための３本以上のスリット溝が設けられ、羽根型に分離された形状を有する。また、電気接点の中央でアークが発生して停滞しないように、電気接点の中央には凹部が設けてある。
【０００５】
上述した電気接点は、高電圧、大電流を開閉遮断するために直接アークにさらされる。電気接点に要求される特性は、遮断容量が大きいこと、耐電圧値が高いこと、耐溶着性に優れることなどが挙げられるが、これらの特性を全て満足することは困難であって、一般には用途に応じて特に重要な特性を重視し、他の特性はある程度犠牲にした材料が用いられる。
【０００６】
例えば、Ｃｒ−Ｃｕの複合金属材料において、遮断容量を大きくするためには導電率が大きいことが必要であり、Ｃｕを多くした組成とすることで対処できるが、耐電圧性能を上げる成分であるＣｒが減るため耐電圧値は低くなり、耐溶着性も低下する。
【０００７】
【発明が解決しようとする課題】
年々、配電の高電圧化が進む中、真空遮断器あるいは真空開閉器等においても、大電流遮断と高耐電圧特性及び耐溶着性能の両立が求められるようになった。例えばＣｒ−Ｃｕ複合金属材料を電気接点に用いる場合には、Ｃｒ量を多くすることで耐電圧値と耐溶着性を向上させることができる。しかし、Ｃｒ量を多くすると導電率は低下し、遮断性能が不十分となり、大電流遮断性能と高耐電圧特性及び耐溶着性能を両立するのは極めて困難であった。
【０００８】
特開２０００−２３５８２５号公報には、偏平状の耐火性金属粒子を有する電極部材の開示があるが、これは高導電性金属と耐火性金属の複合金属を接点面に溶射することにより形成したものである。しかし、溶射法では溶射ガスや大気を巻き込むため、得られた溶射膜はガス含有量が多くなり、電流遮断時のアーク加熱によりガスが放出し、このガスを介してアークが持続してしまい、遮断不能を生ずる恐れがある。また、溶射膜における耐火性金属粒子の大きさや形状の制御が困難で不規則になるため、遮断性能が不安定になる。さらに、溶射膜の形成には多くの時間を要し、生産性あるいはコストの点で問題がある。
【０００９】
本発明の目的は、大電流遮断性能と高耐電圧特性及び耐溶着性能を兼ね備え、製造コストが低く、生産性に優れた電気接点部材とその製法を提供することにある。
【００１０】
【課題を解決するための手段】
そこで本発明者らは、電流遮断を行なう接点面において耐電圧成分が大きな面積を占めるような材料組織を考案した。すなわち、Ｃｒ−Ｃｕ電気接点の場合には、Ｃｒ粒子が偏平板形状を成し、Ｃｕマトリックスの中でＣｒ粒子の偏平面が接点面に平行になるように配向させる。これにより、Ｃｒ含有量を少なくし、高導電率を維持しつつも、接点面にはＣｒ粒子が多く露出するので、高耐電圧特性を得ることができる。また、Ｃｒ粒子とＣｕマトリックスとの化学的結合は弱いため、Ｃｒ粒子の偏平面に垂直方向の強度は小さくなり、耐溶着性が向上する。
【００１１】
本発明の要旨は以下のとおりである。
【００１２】
本発明の電気接点部材は、高導電性金属からなるマトリックス中に偏平板形状を有する耐火性金属粉が分散する組織を成し、前記耐火性金属粉は偏平面が一方向に配向し、前記耐火性金属粉の偏平面と平行な面を接点面とするものである。
【００１３】
本発明に関わる偏平板形状を有する前記耐火性金属粉は、偏平面の最大長さをそれに垂直な面の最小寸法で除した値が３〜３０の範囲にあるものである。
【００１４】
また、本発明の電気接点部材において、偏平板形状を有する前記耐火性金属粉のうちの９０重量％以上は、偏平面が接点面に対して＋４０°〜−４０°の範囲に配向し、また７５重量％以上は、偏平面が接点面に対して＋２０°〜−２０°の範囲に配向するものである。
【００１５】
本発明に関わる前記耐火性金属粉はＣｒ、Ｗ、Ｍｏ、Ｔａ、Ｎｂ、Ｂｅ、Ｈｆ、Ｉｒ、Ｐｔ，Ｚｒ、Ｔｉ、Ｔｅ、Ｓｉ、Ｒｈ及びＲｕの中の１種叉は２種以上の混合物あるいはこれらの化合物からなり、前記高導電性金属はＣｕ、Ａｇ又はＡｕあるいはこれらを主にした合金からなるものである。
【００１６】
また、前記耐火性金属粉は酸素を５０〜２０００ｐｐｍ、Ａｌを５０〜３０００ｐｐｍ、Ｓｉを１００〜２５００ｐｐｍ含むものである。
【００１７】
本発明の電気接点部材は、１５〜４０重量％の前記耐火性金属粉と、６０〜８５重量％の前記高導電性金属からなるものである。
【００１８】
本発明の電気接点部材において、接点面における前記耐火性金属粉が占める面積比は３０〜５０％、接点面と垂直な面における前記耐火性金属粉が占める面積比は１４〜２５％の範囲にあるものである。
【００１９】
本発明の電気接点部材は、含有酸素量が２５００ｐｐｍ以下であり、また、接点面に垂直方向の引張り強さが１５０ＭＰａ以下、接点面に平行方向の引張り強さが１５０ＭＰａ以上であり、さらに、比抵抗は５．５μΩ・ｃｍ以下を有するものである。
【００２０】
本発明の電気接点部材の製法は、前記耐火性金属粉と前記高導電性金属粉との混合粉末を、１２０〜５００ＭＰａで加圧成形して成形体を作製し、該成形体を真空中または不活性雰囲気中において前記高導電性金属粉の融点以下で焼結し，成形過程の加圧面と平行に接点面とするものである。
【００２１】
また、本発明の電気接点部材の製法は、得られた電気接点部材を成形過程と同方向に４００ＭＰａ以上で加圧して緻密化するものである。
【００２２】
本発明の電気接点部材の製法は、前記耐火性金属粉と前記高導電性金属粉との混合粉末を、押出し圧縮成形により連続的な板状あるいは棒状の成形体を作製し、該成形体を不活性雰囲気中において前記高導電性金属の融点以下で連続的に焼結し，押出し方向と平行な面を接点面とするものである。
【００２３】
また、本発明の電気接点部材の製法は、得られた電気接点部材をさらに連続的に圧延処理し，圧延した面と平行に接点面とするもので、この圧延処理は常温あるいは前記高導電性金属の融点以下で行なうものである。
【００２４】
さらに、本発明の電気接点部材の製法は、押出し方向と垂直に打抜き加工することにより所望形状を得るものである。
【００２５】
本発明の電気接点部材の製法において、前記高導電性金属粉の粒径は８０μｍ以下とするものである。
【００２６】
本発明の電気接点部材は、真空バルブにおける一対の固定側電極及び可動側電極を構成する部材として用いられ、この真空バルブは真空遮断器、真空開閉器等に用いられるものである。
【００２７】
本発明における真空バルブは、定格電圧（ｋＶ）と遮断電流実効値（ｋＡ）とを乗算した値ｙが前記真空容器外径ｘ（ｍｍ）に基づいて以下の（１）式によって求められる値以下及び（２）式によって求められる値以上の範囲内にあるものである。
ｙ＝１１．２５ｘ−５２５ …（１）
ｙ＝５．３５ｘ−２４２ …（２）
【００２８】
また、本発明における電気接点は、その直径ｙ（ｍｍ）が定格電圧（ｋＶ）と遮断電流実効値（ｋＡ）とを乗算した値ｘ（ｋＶＡ×１０³）に基づいて以下の（３）式によって求められる値以下及び（４）式によって求められる値以上の範囲内にあるものである。
ｙ＝０．１５ｘ＋２２ …（３）
ｙ＝０．０７７ｘ＋２０ …（４）
【００２９】
さらに、本発明における真空バルブは、その真空容器の外径ｙ（ｍｍ）が前記電気接点の直径ｘ（ｍｍ）に基づいて以下の（５）式によって求められる値以下及び（６）式によって求められる値以上の範囲内にあるものである。
ｙ＝１．２６ｘ＋３０ …（５）
ｙ＝１．２６ｘ＋１０ …（６）
【００３０】
【発明の実施の形態】
本発明の電気接点部材の組織は、高導電性金属からなるマトリックス中に偏平板形状を有する耐火性金属粉が分散し、この耐火性金属粉は偏平面が一方向に配向したものである。この電気接点部材を電極に使用する場合、一方向に配向した耐火性金属粉の偏平面と平行な面を接点面として用いることが望ましい。これにより、耐火性金属含有量を増やすことなく高導電率を維持しつつも、接点面においては耐火性金属粒子が多く露出するので、高耐電圧特性を得ることができる。また、耐火性金属粒子と高導電性金属マトリックスとの化学的結合は弱いため、接点面に垂直方向の強度は小さく、電流遮断時のアーク加熱により電極が溶着した際にも剥離開極しやすくなり、耐溶着性が向上する。
【００３１】
上記の偏平板形状を有する耐火性金属粉は、偏平面の最大長さをそれに垂直な面の最小寸法で除した値が３〜３０の範囲にあることが望ましく、電気接点部材に含まれる耐火性金属粉のうち、９０重量％以上は偏平面が接点面に対して＋４０°〜−４０°の範囲に配向し、また７５重量％以上は偏平面が接点面に対して＋２０°〜−２０°の範囲に配向することで、大電流遮断性能と高耐電圧特性及び耐溶着性能を両立させる上記の効果を発揮することができる。
【００３２】
電気接点部材を構成する耐火性金属粉はＣｒ，Ｗ，Ｍｏ，Ｔａ，Ｎｂ，Ｂｅ，Ｈｆ，Ｉｒ，Ｐｔ，Ｚｒ，Ｔｉ，Ｔｅ，Ｓｉ，Ｒｈ及びＲｕの１種叉は２種以上の混合物あるいはこれらの化合物とし、高導電性金属はＣｕ，ＡｇまたはＡｕあるいはこれらを主にした合金とすることが望ましい。また、耐火性金属粉と高導電性金属との配合比は、耐火性金属粉を１５〜４０重量％、高導電性金属を６０〜８５重量％とすることで、遮断性能、耐電圧特性に優れ、健全な材料組織をもつ電気接点部材が得られる。
【００３３】
耐火性金属粉には、酸素を５０〜２０００ｐｐｍ、Ａｌを５０〜３０００ｐｐｍ、Ｓｉを１００〜２５００ｐｐｍ含むことが望ましく、これらの成分によって遮断時に優れた消弧作用が得られ、遮断性能が向上する。なお、Ａｌ，Ｓｉはそれぞれ酸化物として存在してもよく、高融点で硬質の微細なＡｌ，Ｓｉ酸化物が均一に分散していることにより優れた耐溶着性、耐電圧特性が得られる。酸素、Ａｌ，Ｓｉそれぞれが上記の量より少ないと、Ａｌ，Ｓｉ酸化物の生成量が少なくなり、性能向上に対する効果が小さい。また、上記の量より多いと、遮断時のアーク加熱により酸化物が分解した場合の発生ガス量が多くなり、耐電圧及び遮断性能が低下する。
【００３４】
本発明による電気接点部材における耐火性金属粉が占める面積比は、接点面では３０〜５０％、接点面と垂直な面では１４〜２５％の範囲にあることが望ましく、これにより高導電率を維持しながら高耐電圧特性を発揮することができ、耐溶着性も向上する。
【００３５】
また、この電気接点部材の含有酸素量は２５００ｐｐｍ以下とすることで、電流遮断時のガス放出を抑制し、ガスを介したアーク持続による遮断不能を防止することができる。
【００３６】
さらに、接点面に垂直方向の引張り強さは１５０ＭＰａ以下、接点面に平行方向の引張り強さは１５０ＭＰａ以上であることで、電流遮断時のアーク加熱による溶着時に開極方向に剥離しやすくなり、耐溶着性が向上する。
【００３７】
なお、電気接点部材の比抵抗は５．５μΩ・ｃｍ以下であることが望ましく、電気的特性は高導電性金属の含有量にほぼ依存するため、異方性はない。この比抵抗値を有することで、良好な遮断性能を維持することができる。
【００３８】
電気接点部材の製法は、耐火性金属粉と高導電性金属粉との混合粉末を、圧力１２０〜５００ＭＰａで加圧成形して成形体を作製し、この成形体を真空中または不活性雰囲気中において高導電性金属粉の融点以下で焼結することが望ましい。成形圧力が１２０ＭＰａより小さいと成形密度が小さくなり成形体が崩れやすく、５００ＭＰａより大きいと金型寿命が短くなり生産性も低下する。また、真空中または不活性雰囲気中において焼結することにより、健全な焼結組織と適正なガス含有量が得られる。偏平板形状の耐火性金属粉は，成形過程の加圧面に平行に配向する傾向にあるため，加圧面に平行な面を接点面として用いることが望ましく，これにより目的とする特性が得られる。
【００３９】
さらに、得られた電気接点部材を成形過程と同方向に圧力４００ＭＰａ以上で加圧することにより、より緻密化することができ、電極性能の安定化につながる。また，偏平板形状を有する耐火性金属粉の配向性が強まり，目的とする特性がより向上する。
【００４０】
また、本発明の電気接点部材の製法は、耐火性金属粉と高導電性金属粉との混合粉末を、押出し圧縮成形によって連続的な板状あるいは棒状の成形体を作製し、この成形体を不活性雰囲気中において高導電性金属の融点以下で連続的に焼結してもよい。この方法により、低コストで生産性の高い電気接点部材の製造が可能となる。また，偏平板形状の耐火性金属粉は，押出し方向と平行に配向する傾向にあるため，押出し方向に平行な面を接点面として用いることが望ましく，これにより目的とする特性が得られる。
【００４１】
得られた電気接点部材を、さらに連続的に圧延処理することにより緻密化することができ、電極性能の安定化が可能となる。この圧延処理は常温でも可能であるが、高導電性金属の融点以下の温間圧延によって、割れなどの材料欠陥を防止することができる。また，圧延により偏平板形状を有する耐火性金属粉の配向性が強まり，目的とする特性がより向上する。
【００４２】
さらに、得られた電気接点部材を押出し方向に垂直に打抜き加工することによって，短時間で効率よく所望の電極形状を得ることができる。
上記の電気接点部材の原料となる高導電性金属粉の粒径は、８０μｍ以下とすることが望ましい。高導電性金属粉の粒径がこれより大きいと、混合粉末の成形過程において、耐火性金属粉に配向性を持たせることが困難となり、目的とする材料特性が得られなくなる。
【００４３】
本発明における真空バルブは、定格電圧（ｋＶ）と遮断電流実効値（ｋＡ）とを乗算した値ｙが前記真空容器外径ｘ（ｍｍ）に基づいて以下の（１）式によって求められる値以下及び（２）式によって求められる値以上の範囲内にあることが好ましい。
ｙ＝１１．２５ｘ−５２５ …（１）
ｙ＝５．３５ｘ−２４２ …（２）
【００４４】
また、本発明における電気接点は、その直径ｙ（ｍｍ）が定格電圧（ｋＶ）と遮断電流実効値（ｋＡ）とを乗算した値ｘ（ｋＶＡ×１０³）に基づいて以下の（３）式によって求められる値以下及び（４）式によって求められる値以上の範囲内にあることが好ましい。
ｙ＝０．１５ｘ＋２２ …（３）
ｙ＝０．０７７ｘ＋２０ …（４）
【００４５】
さらに、本発明における真空バルブは、その真空容器の外径ｙ（ｍｍ）が前記電気接点の直径ｘ（ｍｍ）に基づいて以下の（５）式によって求められる値以下及び（６）式によって求められる値以上の範囲内にあることが好ましい。
ｙ＝１．２６ｘ＋３０ …（５）
ｙ＝１．２６ｘ＋１０ …（６）
【００４６】
又、本発明は、真空容器内に固定側電極と可動側電極とを備えた真空バルブと、該真空バルブ内の前記固定側電極と前記可動側電極との各々に前記真空バルブ外に接続された絶縁ロッドを介して前記可動側電極を駆動する開閉手段とを備えた真空遮断器において、前記真空バルブが前述に記載の真空バルブからなることを特徴とする。
以下、実施例により本発明を具体的に説明する。
【００４７】
[実施例１]
本発明に関する実施例として、耐火性金属をＣｒ、高導電性金属をＣｕとし、組成が２５Ｃｒ−７５Ｃｕの電気接点部材を作製した。この電気接点部材の製造方法は次の通りである。
【００４８】
耐火性金属であるＣｒ粉末は、所定の隙間寸法に設定したローラー圧縮により偏平化し、偏平面の最大長さをそれに垂直な面の最小寸法で除した値(以下、アスペクト比という)が３，１０，３０，４０（比較例）のＣｒ偏平粉を作製した。又、別の比較例として、原料Ｃｒ粉のままを用いてアスペクト比1とした。なお、用いたＣｒ粉末には酸素が１１００ｐｐｍ、Ａｌが８００ｐｐｍ、Ｓｉが４４０ｐｐｍ含まれている。
【００４９】
高導電性金属であるＣｕ粉末には，粒径が８０μｍ以下のものと８０μｍ以上のものを用いた。
上記のＣｒ偏平粉とＣｕ粉末を組合せ、表１に示す１０種類の電気接点部材を作製した。
【表１】

まず、Ｃｒ偏平粉とＣｕ粉末を重量比で２５：７５の割合にＶ型混合器で混合した。次にこの混合粉を直径６０ｍｍの金型に充填し、油圧プレスにより２５０ＭＰａの圧力を直径６０ｍｍの円面にかけて加圧成形した。成形体の寸法は直径６０ｍｍ×厚さ１２ｍｍで、相対密度は７３％であった。これを６．７×１０^-3Ｐａ以下の真空中で１０５０℃×１２０分間加熱し、表1に示す電気接点部材を作製した。焼結加熱後の相対密度はいずれも９７〜９８％であった。
【００５０】
図1は、作製した電気接点部材の組織の一例として示したもので、試料番号Ｃ（Ｃｒ粉アスペクト比：１０，Ｃｕ粉粒径：８０μｍ以下）の組織写真である。電気接点部材の円面（以下、接点面という）とそれに垂直な断面について、光学顕微鏡を用いて観察した。
【００５１】
図1において、（a）は接点面と平行な面の組織、(ｂ)は接点面と垂直な断面の組織である。（a）の接点面ではＣｒ粒子の偏平面が比較的大きな面積を占め、また(ｂ)の接点面に垂直な断面ではＣｒ粒子の偏平面が接点面にほぼ平行に配向していることが確認された。これにより、偏平板形状を有するＣｒ粉は加圧方向に垂直に配向する傾向にあり、加圧面と平行に接点面とすることで、本発明の目的とする材料組織が得られることが実証された。
【００５２】
得られた１０種類の電気接点部材の接点面と、それに垂直な断面を光学顕微鏡により観察し、接点面に対して±４０°及び±２０°の範囲に配向しているＣｒ粒子の割合を求めた。Ｃｒ粒子の割合はそれぞれの角度範囲にあるＣｒの面積を画像処理により求め、含まれるすべてのＣｒに対する重量比として算出した。
【００５３】
表1にそれぞれの角度範囲にあるＣｒの割合を示すが、Ｃｕの粒径が８０μｍ以上の場合には、Ｃｒ粉のアスペクト比が３〜４０の場合に９０重量％以上が＋４０°〜−４０°の範囲に配向し、さらに７５重量％以上は＋２０°〜−２０°の範囲に配向することが確認された。
【００５４】
これに対し、Ｃｕの粒径が８０μｍ以下の場合には、Ｃｒ粉のアスペクト比が４０の場合にも＋４０°〜−４０°の範囲のＣｒは９０重量％に満たず、＋２０°〜−２０°の範囲のＣｒも７５重量％に満たないことが確認された。
以上から、偏平Ｃｒ粉末を所望方向に配向するには、Ｃｕの粒径は８０μｍ以下が望ましいことが証明された。
【００５５】
得られた電気接点部材の接点面及びそれに垂直な断面における、Ｃｒが占める面積の割合(面積占有率)を画像処理により求めた結果を表１に併記するが、Ｃｕの粒径が８０μｍ以下の場合には、Ｃｒ粉のアスペクト比が３〜４０の場合に接点面で３０％以上、垂直断面で１４〜２５％の面積占有率を持つことが確認された。ただし、Ｃｒ粉のアスペクト比が４０の場合(試料番号Ｅ)には、接点面におけるＣｒの面積占有率が５０％以上となり、電極として用いた場合に相手側電極との間の接触抵抗が大きくなり、通電性能が低下するため好ましくない。従って、Ｃｒ粉のアスペクト比は３〜３０が望ましい。
【００５６】
なお、以上の傾向は耐火性金属がＣｒ以外のＷ、Ｍｏ、Ｔａ、Ｎｂ、Ｂｅ、Ｈｆ、Ｉｒ、Ｐｔ、Ｚｒ、Ｔｉ、Ｔｅ、Ｓｉ、Ｒｈ及びＲｕの中の１種叉は２種以上の混合物あるいはこれらの化合物であり、高導電性金属がＣｕ以外のＡｇまたはＡｕあるいはこれらを主にした合金である場合にも同様であることを確認した。
【００５７】
[実施例２]
本発明に関する別の実施例として、耐火性金属をＣｒ、高導電性金属をＣｕとし、Ｃｒ含有量を１０重量％から４５重量％まで変えて、５種類の電気接点部材を作製した。Ｃｒ粉のアスペクト比は１５、Ｃｕ粉末の粒径は８０μｍ以下とした。この電気接点部材の製造方法は、実施例１と同様である。得られた電気接点部材の焼結加熱後の相対密度はいずれも９７〜９８％であった。
【００５８】
表２に，作製した電気接点部材の組成と共に、接点面に対して±４０°及び±２０°の範囲に配向しているＣｒ粒子の割合、また接点面とそれに垂直な断面におけるＣｒ面積占有率を示す。
【表２】

いずれの組成においても、９０重量％以上のＣｒが＋４０°〜−４０°の範囲に配向し、さらに７５重量％以上は＋２０°〜−２０°の範囲に配向することが確認された。しかし、組成１０Ｃｒ−Ｃｕ（試料Ｋ）では接点面のＣｒ面積占有率が３０％以下、垂直断面は１４％以下となり、遮断性能と高耐電圧特性を両立させる本発明の目的を達成することが出来なくなる。また、組成４５Ｃｒ−Ｃｕ(試料Ｏ)では接点面が５０％以上となり、通電性能が低下するため好ましくない。従って、組成はＣｒが１５〜４０重量％、Ｃｕが６０〜８５重量％が適当であることが確認された。
【００５９】
なお、以上の傾向は耐火性金属がＣｒ以外のＷ、Ｍｏ、Ｔａ、Ｎｂ、Ｂｅ、Ｈｆ、Ｉｒ、Ｐｔ，Ｚｒ、Ｔｉ、Ｔｅ、Ｓｉ、Ｒｈ及びＲｕの中の１種叉は２種以上の混合物あるいはこれらの化合物であり、高導電性金属がＣｕ以外のＡｇまたはＡｕあるいはこれらを主にした合金である場合にも同様であることを確認した。
【００６０】
[実施例３]
本発明に関する第３実施例として、実施例１及び実施例２で作製した電気接点部材のうち、試料番号Ａ〜Ｄ及びＬ〜Ｎについて、接点面に対して垂直方向と平行方向の引張り強さ及び比抵抗を測定した。
【００６１】
表３に、それぞれの測定結果を示した。
【表３】

【００６２】
原料粉末のままのＣｒを用いた試料番号Ａに比べて、いずれも接点面に垂直方向の引張り強さは１５０ＭＰａ以下であるのに対し、平行方向の引張り強さは１５０ＭＰａ以上の値を示した。従って、接点面に対して垂直方向の強度が小さいことから、相手側電極と溶着した際に剥離破壊しやすく、耐溶着性が向上する。
【００６３】
また、比抵抗には顕著な異方性は見られない。これは、電気的特性は組成によってほぼ支配されるため、Ｃｒ粉末が偏平形状をなしていても導電性に方向性はなく、遮断性能を従来組織と同等に維持できることを示す。
【００６４】
以上から、本発明に関する電気接点部材は、接点面に対して垂直方向に比較的剥離しやすく、導電性には異方性がないことが確認された。
【００６５】
[実施例４]
本発明に関する第４実施例として、実施例１及び実施例２で作製した電気接点部材のうち、試料番号Ａ〜Ｅ及びＫ〜Ｏの部材を用いて、真空バルブに適用するための電極を作製した。
【００６６】
図２は、作製した電極の構造を示す。図２において、１は電気接点、２はアークに駆動力を与えて停滞させないようにするためのスパイラル溝、３はステンレス製の補強板、４は電極棒、５はろう材である。
電極の作製方法は次の通りである。実施例１及び実施例２で作製した電気接点部材を機械加工により所望形状に加工して電気接点１を得る。電極棒４を無酸素銅で、また、補強板３をＳＵＳ３０４であらかじめ機械加工により作製しておき、電気接点１及び補強板３の中央孔と電極棒４の凸部とを、ろう材５を介して嵌め合わせ、また電気接点１と補強板３との間にもろう材５を載置し、これを８．２×１０^-4Ｐａ以下の真空中で９８０℃×８分間加熱し、図２に示す電極を作製した。なお、この電極は定格電圧７．２ｋＶ、定格電流６００Ａ、定格遮断電流２０ｋＡ用の真空バルブに用いられる電極である。
【００６７】
[実施例５]
実施例４で作製した電極を搭載した真空バルブを作製した。真空バルブの仕様は定格電圧７．２ｋＶ、定格電流６００Ａ、定格遮断電流２０ｋＡである。
図３は、本実施例に係わる真空バルブの構造を示す。図３において、１ａ，１ｂはそれぞれ固定側電気接点、可動側電気接点、３ａ，３ｂは補強板、４ａ，４ｂはそれぞれ固定側電極棒、可動側電極棒で、これらをもってそれぞれ固定側電極６ａ、可動側電極６ｂを構成する。可動側電極６ｂは、遮断時の金属蒸気等の飛散を防ぐ可動側シールド８を介して可動側ホルダー１２にろう付け接合される。これらは、固定側端板９ａ、可動側端板９ｂ、及び絶縁筒１３によって高真空にろう付け封止され、固定側電極６ａ及び可動側ホルダー１２のネジ部をもって外部導体と接続される。絶縁筒１３の内面には、遮断時の金属蒸気等の飛散を防ぐシールド７が設けられ、また、可動側端板９ｂと可動側ホルダー１２の間には摺動部分を支えるためのガイド１１が設けられる。可動側シールド８と可動側端板９ｂの間にはべローズ１０が設けられ、真空バルブ内を真空に保ったまま可動側ホルダー１２を上下させ、固定側電極６ａと可動側電極６ｂを開閉させることが出来る。本実施例では、固定側電極６ａ及び可動側電極６ｂに、実施例４で作製した図２に示す構造の電極を用いて、図３に示す真空バルブを作製した。
【００６８】
[実施例６]
実施例５で作製した真空バルブを真空遮断器に組み込んで、各種性能試験を実施した結果を表４に示す。
【表４】

【００６９】
表４におけるそれぞれの性能は、原料のままのＣｒを用いた従来材の組織を有する試料Ａの値を１として相対比較して表した。
【００７０】
試料Ａ〜Ｅにおいて、Ｃｒ粉のアスペクト比が変化しても遮断性能は変わらない。これは表３に示すように比抵抗にほとんど変化が無いためである。一方、アスペクト比が大きくなるにつれて耐電圧性能は大きくなる。これは表１に示すように、接点面におけるＣｒの面積占有率が大きくなるためである。また、アスペクト比が大きくなるにつれて耐溶着性能も大きくなるが、これはＣｒ面積占有率が大きいことと、表３に示すように接点面に垂直方向の引張り強さが小さくなり、剥離開離しやすいためである。ただし、Ｃｒ粉のアスペクト比が４０である試料Ｅは、接点面におけるＣｒ面積占有率が大きいために、電極間の接触抵抗が大きくなり、通電抵抗が大きく好ましくない。従って、Ｃｒ粉のアスペクト比は３〜３０の場合に、遮断性能を維持したまま、耐電圧特性と耐溶着性能を向上させることに効果があることが実証された。
【００７１】
試料Ｋ〜Ｏにおいて、試料Ｎの遮断性能は従来組織をもつ試料Ａより小さく０．９であるが、定格遮断電流２０ｋＡ用真空遮断器への適用は可能である。しかし、試料Ｏは遮断性能不足で、定格遮断電流２０ｋＡ用真空遮断器への適用は困難であった。また、Ｃｒ量が少なくなると、耐電圧性能が低下し、それに伴うアーチ再発孤により遮断性能が低下し、試料Ｋは定格電圧７．２ｋＶの真空遮断器への適用は困難であった。従って、Ｃｒ量は１５〜４０重量％が適当である。
なお、実施例１及び実施例２で作製した電気接点部材を再度金型に入れ、４００，６００，及び８００ＭＰａで加圧した電気接点を用い、実施例４と同様の方法で作製した電極についても同様の性能評価を行った。ここで、いずれの圧力で加圧した電気接点部材も、相対密度は９８．５％以上であった。その結果、上記の結果と同様の傾向が得られ、遮断性能は更に安定化する傾向にあった。これは焼結後に再度加圧することで緻密化が進み、内部欠陥や内在ガス量が減少したためである。
【００７２】
以上から、本発明に係わる電気接点部材は、遮断性能、高耐電圧特性、耐溶着性を両立させるために有益であることが実証された。
【００７３】
[実施例７]
本発明に関する別の製造方法として、実施例１及び実施例２と同様の電気接点部材を作製した。図４は、本実施例の製造方法と製造装置を示す概略図である。図４において、１４は原料混合粉末１５を入れるための容器、１６は容器１４から充填された原料混合粉末１５を連続的に押出し成形するための成形機、１７は回転しながら原料混合粉末１５を成形すると共に送り出すためのローラー、１８は成形された板状の連続成形体、１９は連続成形体１８を不活性雰囲気中で連続して加熱焼結するためのトンネル炉、２０は加熱焼結して得られた連続焼結体、２１は連続焼結体２０を圧延して緻密化するための圧延ローラー、２２は圧延された電気接点部材、２３は電気接点部材２２から所望形状の電気接点２４を打ち抜くための金型、２５は打ち抜き加工により得られた電気接点２４を連続的に搬送移動するためのベルトである。
【００７４】
本実施例における成形圧力、焼結温度、焼結後の圧延時の圧力等は、実施例１及び実施例２とほぼ同様になるように設定して行った。
【００７５】
本実施例で得られた電気接点部材の組織、引張り強さ、比抵抗などについて検討したところ、実施例１及び実施例２で得られた電気接点部材とほぼ同等の結果が得られた。
【００７６】
従って本製造方法によれば、連続して大量の電気接点部材の製造が可能で、低コストで生産性に優れ、さらに遮断性能、高耐電圧特性、耐溶着性を両立した本発明の目的に合致した電気接点部材が得られることが確認された。
【００７７】
[実施例８]
表５は、試料Ｂの部材を電気接点１ａ，１ｂに用いて作製した、各種定格の真空バルブの諸元を示すものである。
【表５】

【００７８】
図５は、遮断電圧電流実効値（ｙ）と真空容器外径（ｘ）との関係を示す線図である。遮断電圧電流実効値は遮断電圧（ｋＶ）と遮断電流実効値（ｋＡ)とを乗算したものである。図５に示すように、遮断電圧電流実効値（y)は１１．２５ｘ−５２５と５．３５ｘ−２４２とで求められる値の間に入るように遮断電圧電流実効値に対して真空容器外径とするのが好ましい。
【００７９】
図６は、電気接点直径（ｙ）と遮断電圧電流実効値（ｘ）との関係を示す線図である。遮断電圧電流実効値（ｘ）に対して電気接点直径（ｙ）は、０．１５ｘ＋２２と０．０７７ｘ＋２０とで求められる値の間に入るように設定することが好ましい。
【００８０】
図７は、真空容器外径（ｙ）と電気接点直径（ｘ）との関係を示す線図である。真空容器外径（ｙ）は１．２６ｘ＋３０と１．２６ｘ＋１０とで求められる値の間に設定することが好ましい。本実施例においては、ｙ＝１．２６ｘ＋１９．６によって求められる値にほぼ設定されている。
【００８１】
【発明の効果】
本発明による電気接点部材は、偏平板形状を有する耐火性金属粉が高導電性金属からなるマトリックスの中で接点面に平行に配向した組織を有するため、接点面における耐火性金属粉の占有面積が大きくなり、遮断性能を低下させずに、高耐電圧特性及び耐溶着性能を向上させることが出来る。
また、本発明による製法によれば、上記の材料組織をもつ電気接点部材が効率よく大量生産できるため、製造コストの低減が図れる。
【図面の簡単な説明】
【図１】本発明の実施例１に係わる電気接点部材の組織の一例を示す写真である。
【図２】本発明の実施例４に係わる電極の構造を示す。
【図３】本発明の実施例５に係わる真空バルブの構造を示す。
【図４】本発明の実施例７に係わる製造方法と製造装置を示す。
【図５】本発明の実施例８に係わる真空バルブの遮断電圧電流実効値と真空容器外径との関係を示す。
【図６】本発明の実施例８に係わる真空バルブの電気接点直径と遮断電圧電流実効値との関係を示す。
【図７】本発明の実施例８に係わる真空バルブの真空容器外径と電気接点直径との関係を示す。
【符号の説明】
１…電気接点、１ａ…固定側電気接点、１ｂ…可動側電気接点、２…スパイラル溝、３，３ａ，３ｂ…補強板、４…電極棒、５…ろう材、６ａ…固定側電極、６ｂ…可動側電極、７…シールド、８…可動側シールド、９ａ…固定側端板、９ｂ…可動側端板、１０…ベローズ、１１…ガイド、１２…可動側ホルダー、１３…絶縁筒、１４…容器、１５…原料混合粉末、１６…成形機、１７…ローラー、１８…連続成形体、１９…トンネル炉、２０…連続焼結体、２１…圧延ローラー、２２…電気接点部材、２３…金型、２４…電気接点、２５…ベルト。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel electric contact member used for a vacuum circuit breaker, a vacuum switch, and the like, a manufacturing method thereof, a vacuum valve using the same, and a vacuum circuit breaker.
[0002]
[Prior art]
An electrode structure in a vacuum valve installed in a vacuum circuit breaker or the like is composed of a pair of fixed side electrodes and movable side electrodes. The structure of the fixed side and movable side electrodes includes an electrical contact and an electrode rod connected to the electrical contact, and a plate made of stainless steel or the like is often provided as a reinforcing plate on the back surface of the electrical contact.
[0003]
As an electric contact member for high current and high voltage interruption, a composite metal material of Cr—Cu is often used.
[0004]
This electrical contact manufacturing method is an electrical contact member manufactured by a so-called powder metallurgy method in which a metal powder of each component or a mixed powder thereof is molded into a simple shape such as a disk with a predetermined composition and then sintered. Further, it is machined into a predetermined shape. The electrical contact is provided with three or more slit grooves for applying a driving force to the generated arc and moving the arc to the outer periphery of the electrode without stagnation in one place, and separated into a blade shape. Has a shape. In addition, a recess is provided at the center of the electrical contact so that an arc is generated at the center of the electrical contact and does not stagnate.
[0005]
The above-described electrical contacts are directly exposed to an arc to open and close high voltage and large current. The characteristics required for electrical contacts include a large breaking capacity, a high withstand voltage value, and excellent welding resistance, but it is difficult to satisfy all of these characteristics. A material that emphasizes particularly important characteristics depending on the application and sacrifices some of the other characteristics is used.
[0006]
For example, in a composite metal material of Cr—Cu, in order to increase the breaking capacity, it is necessary that the electrical conductivity is large, and it can be dealt with by increasing the composition of Cu, but it is a component that increases the withstand voltage performance. Since Cr decreases, the withstand voltage value decreases and the welding resistance also decreases.
[0007]
[Problems to be solved by the invention]
As the distribution of voltage increases year by year, both a high current interruption, a high withstand voltage characteristic, and a welding resistance have been required for vacuum circuit breakers or vacuum switches. For example, when a Cr—Cu composite metal material is used for an electrical contact, the withstand voltage value and the welding resistance can be improved by increasing the amount of Cr. However, if the amount of Cr is increased, the conductivity is lowered, the interruption performance becomes insufficient, and it has been extremely difficult to achieve both high current interruption performance, high withstand voltage characteristics, and welding resistance.
[0008]
Japanese Patent Laid-Open No. 2000-235825 discloses an electrode member having flat refractory metal particles, which is formed by spraying a composite metal of a highly conductive metal and a refractory metal on a contact surface. Is. However, in the thermal spraying method, since the sprayed gas and the atmosphere are involved, the obtained sprayed film has a high gas content, the gas is released by arc heating at the time of interrupting the current, and the arc continues through this gas, May cause inability to shut off. Moreover, since the control of the size and shape of the refractory metal particles in the sprayed film is difficult and irregular, the blocking performance becomes unstable. Furthermore, it takes a lot of time to form the sprayed film, which is problematic in terms of productivity and cost.
[0009]
An object of the present invention is to provide an electrical contact member having both a high current interruption performance, a high withstand voltage characteristic, and a welding performance, a low manufacturing cost, and an excellent productivity, and a method for producing the electrical contact member.
[0010]
[Means for Solving the Problems]
Therefore, the present inventors have devised a material structure in which the withstand voltage component occupies a large area on the contact surface for interrupting current. That is, in the case of a Cr—Cu electrical contact, the Cr particles have a flat plate shape and are oriented in the Cu matrix so that the flat surface of the Cr particles is parallel to the contact surface. Thereby, since a large amount of Cr particles are exposed on the contact surface while reducing the Cr content and maintaining high conductivity, a high withstand voltage characteristic can be obtained. Further, since the chemical bond between the Cr particles and the Cu matrix is weak, the strength in the direction perpendicular to the uneven plane of the Cr particles is reduced, and the welding resistance is improved.
[0011]
The gist of the present invention is as follows.
[0012]
The electrical contact member of the present invention has a structure in which a refractory metal powder having a flat plate shape is dispersed in a matrix made of a highly conductive metal, and the refractory metal powder has a flat plane oriented in one direction, A surface parallel to the flat surface of the refractory metal powder is used as the contact surface.
[0013]
In the refractory metal powder having the flat plate shape according to the present invention, a value obtained by dividing the maximum length of the flat surface by the minimum dimension of the surface perpendicular thereto is in the range of 3 to 30.
[0014]
In the electrical contact member of the present invention, 90% by weight or more of the refractory metal powder having a flat plate shape has a flat plane oriented in a range of + 40 ° to −40 ° with respect to the contact surface. In the case of 75% by weight or more, the flat plane is oriented in the range of + 20 ° to −20 ° with respect to the contact surface.
[0015]
The refractory metal powder according to the present invention is one or more of Cr, W, Mo, Ta, Nb, Be, Hf, Ir, Pt, Zr, Ti, Te, Si, Rh and Ru. It consists of a mixture or a compound thereof, and the highly conductive metal is composed of Cu, Ag or Au or an alloy mainly composed of these.
[0016]
The refractory metal powder contains 50 to 2000 ppm of oxygen, 50 to 3000 ppm of Al, and 100 to 2500 ppm of Si.
[0017]
The electrical contact member of the present invention comprises 15 to 40% by weight of the refractory metal powder and 60 to 85% by weight of the highly conductive metal.
[0018]
In the electrical contact member of the present invention, the area ratio of the refractory metal powder in the contact surface is 30 to 50%, and the area ratio of the refractory metal powder in the plane perpendicular to the contact surface is in the range of 14 to 25%. There is something.
[0019]
The electrical contact member of the present invention has an oxygen content of 2500 ppm or less, a tensile strength in a direction perpendicular to the contact surface of 150 MPa or less, a tensile strength in a direction parallel to the contact surface of 150 MPa or more, and The resistance is 5.5 μΩ · cm or less.
[0020]
The method for producing an electrical contact member of the present invention is to produce a molded body by pressing the mixed powder of the refractory metal powder and the highly conductive metal powder at 120 to 500 MPa, and the molded body in vacuum or Sintering is performed at a temperature equal to or lower than the melting point of the highly conductive metal powder in an inert atmosphere, and the contact surface is formed in parallel with the pressing surface in the molding process.
[0021]
Moreover, the manufacturing method of the electrical contact member of this invention pressurizes the obtained electrical contact member in the same direction as a shaping | molding process at 400 Mpa or more, and densifies.
[0022]
The method for producing an electrical contact member of the present invention is to produce a continuous plate-shaped or rod-shaped molded body by extruding and compressing a mixed powder of the refractory metal powder and the highly conductive metal powder. Sintering is continuously performed in an inert atmosphere at a temperature equal to or lower than the melting point of the highly conductive metal, and a surface parallel to the extrusion direction is used as a contact surface.
[0023]
Further, the method for producing an electrical contact member of the present invention is a method in which the obtained electrical contact member is further continuously rolled to form a contact surface parallel to the rolled surface. It is performed below the melting point of the metal.
[0024]
Furthermore, the manufacturing method of the electrical contact member of the present invention is to obtain a desired shape by punching perpendicularly to the extrusion direction.
[0025]
In the method for producing an electrical contact member of the present invention, the highly conductive metal powder has a particle size of 80 μm or less.
[0026]
The electric contact member of the present invention is used as a member constituting a pair of fixed side electrode and movable side electrode in a vacuum valve, and this vacuum valve is used for a vacuum circuit breaker, a vacuum switch and the like.
[0027]
In the vacuum valve according to the present invention, a value y obtained by multiplying the rated voltage (kV) and the breaking current effective value (kA) is not more than a value obtained by the following equation (1) based on the vacuum vessel outer diameter x (mm). And it exists in the range beyond the value calculated | required by (2) Formula.
y = 11.25x−525 (1)
y = 5.35x-242 (2)
[0028]
In the electrical contact according to the present invention, the diameter y (mm) is a value x (kVA × 10) obtained by multiplying the rated voltage (kV) and the breaking current effective value (kA).^Three) Based on the following formula (3) or less and the value obtained by formula (4) or more.
y = 0.15x + 22 (3)
y = 0.077x + 20 (4)
[0029]
Furthermore, the vacuum valve in the present invention is obtained by the following equation (5) and the value obtained by the following equation (5) based on the outer diameter y (mm) of the vacuum vessel based on the diameter x (mm) of the electrical contact. It is within a range that is greater than or equal to the value obtained.
y = 1.26x + 30 (5)
y = 1.26x + 10 (6)
[0030]
DETAILED DESCRIPTION OF THE INVENTION
In the structure of the electrical contact member of the present invention, a refractory metal powder having a flat plate shape is dispersed in a matrix made of a highly conductive metal, and the refractory metal powder has a flat plane oriented in one direction. When this electrical contact member is used for an electrode, it is desirable to use a surface parallel to the flat surface of the refractory metal powder oriented in one direction as the contact surface. Thereby, while maintaining high conductivity without increasing the refractory metal content, a large amount of refractory metal particles are exposed on the contact surface, so that a high withstand voltage characteristic can be obtained. In addition, since the chemical bond between the refractory metal particles and the highly conductive metal matrix is weak, the strength in the direction perpendicular to the contact surface is small, and it is easy to peel off and open even when the electrode is welded by arc heating during current interruption. Thus, the welding resistance is improved.
[0031]
The refractory metal powder having the above-described flat plate shape preferably has a value obtained by dividing the maximum length of the flat plane by the minimum dimension of the plane perpendicular thereto within a range of 3 to 30, and the refractory metal contained in the electrical contact member Of the conductive metal powder, 90% by weight or more has a flat plane oriented in the range of + 40 ° to −40 ° with respect to the contact surface, and 75% by weight or more has a flat surface of + 20 ° to −20 with respect to the contact surface. By orienting in the range of °, the above-described effect of achieving both a large current interruption performance, a high withstand voltage characteristic, and a welding resistance performance can be exhibited.
[0032]
The refractory metal powder constituting the electrical contact member is one or a mixture of Cr, W, Mo, Ta, Nb, Be, Hf, Ir, Pt, Zr, Ti, Te, Si, Rh and Ru. Alternatively, these compounds are used, and the highly conductive metal is preferably Cu, Ag, Au, or an alloy mainly composed of these. Moreover, the blending ratio of the refractory metal powder and the highly conductive metal is such that the refractory metal powder is 15 to 40% by weight and the highly conductive metal is 60 to 85% by weight, so that the breaking performance and the withstand voltage characteristics are improved. An electrical contact member having an excellent and sound material structure can be obtained.
[0033]
The refractory metal powder preferably contains 50 to 2000 ppm of oxygen, 50 to 3000 ppm of Al, and 100 to 2500 ppm of Si, and these components provide an excellent arc extinguishing action at the time of interruption and improve the interruption performance. Al and Si may exist as oxides respectively, and excellent welding resistance and voltage resistance characteristics can be obtained by uniformly dispersing hard fine Al and Si oxides having a high melting point. If each of oxygen, Al, and Si is less than the above amounts, the amount of Al and Si oxide generated is reduced, and the effect on performance improvement is small. On the other hand, when the amount is larger than the above amount, the amount of gas generated when the oxide is decomposed by arc heating at the time of interruption increases, and the withstand voltage and the interruption performance deteriorate.
[0034]
The area ratio occupied by the refractory metal powder in the electrical contact member according to the present invention is preferably in the range of 30 to 50% on the contact surface and in the range of 14 to 25% on the surface perpendicular to the contact surface. High withstand voltage characteristics can be exhibited while maintaining the resistance to welding.
[0035]
In addition, by setting the oxygen content of the electrical contact member to 2500 ppm or less, it is possible to suppress gas release at the time of current interruption and to prevent interruption due to arc continuation through the gas.
[0036]
Furthermore, the tensile strength in the direction perpendicular to the contact surface is 150 MPa or less, and the tensile strength in the direction parallel to the contact surface is 150 MPa or more, so that it is easy to peel in the opening direction at the time of welding by arc heating during current interruption, Improved welding resistance.
[0037]
Note that the specific resistance of the electrical contact member is desirably 5.5 μΩ · cm or less, and the electrical characteristics substantially depend on the content of the highly conductive metal, so that there is no anisotropy. By having this specific resistance value, good blocking performance can be maintained.
[0038]
The electrical contact member is produced by pressing a mixed powder of a refractory metal powder and a highly conductive metal powder at a pressure of 120 to 500 MPa to produce a molded body, and then the molded body in a vacuum or in an inert atmosphere. It is desirable to sinter at or below the melting point of the highly conductive metal powder. If the molding pressure is less than 120 MPa, the molding density becomes small and the molded body tends to collapse, and if it exceeds 500 MPa, the mold life is shortened and the productivity is also lowered. Further, by sintering in vacuum or in an inert atmosphere, a sound sintered structure and an appropriate gas content can be obtained. Since the flat plate-shaped refractory metal powder tends to be oriented parallel to the pressing surface in the forming process, it is desirable to use a surface parallel to the pressing surface as the contact surface, thereby obtaining the desired characteristics.
[0039]
Furthermore, by pressurizing the obtained electrical contact member in the same direction as the molding process at a pressure of 400 MPa or more, it can be further densified, leading to stabilization of electrode performance. In addition, the orientation of the refractory metal powder having a flat plate shape is enhanced, and the intended characteristics are further improved.
[0040]
In addition, the method for producing the electrical contact member of the present invention is to produce a continuous plate-shaped or rod-shaped molded body by extrusion compression molding a mixed powder of a refractory metal powder and a highly conductive metal powder. You may sinter continuously in the inert atmosphere below the melting point of a highly conductive metal. This method makes it possible to manufacture an electrical contact member with low cost and high productivity. In addition, the flat plate-shaped refractory metal powder tends to be oriented parallel to the extrusion direction, and therefore, it is desirable to use a plane parallel to the extrusion direction as the contact surface, thereby obtaining the desired characteristics.
[0041]
The obtained electrical contact member can be further densified by continuously rolling, and the electrode performance can be stabilized. Although this rolling treatment is possible even at room temperature, material defects such as cracks can be prevented by warm rolling below the melting point of the highly conductive metal. In addition, the orientation of the refractory metal powder having a flat plate shape is strengthened by rolling, and the intended characteristics are further improved.
[0042]
Furthermore, by punching the obtained electrical contact member perpendicularly to the extrusion direction, a desired electrode shape can be efficiently obtained in a short time.
The particle size of the highly conductive metal powder used as the raw material for the electrical contact member is desirably 80 μm or less. If the particle size of the highly conductive metal powder is larger than this, it will be difficult to impart orientation to the refractory metal powder in the process of forming the mixed powder, and the desired material properties will not be obtained.
[0043]
In the vacuum valve according to the present invention, a value y obtained by multiplying the rated voltage (kV) and the breaking current effective value (kA) is not more than a value obtained by the following equation (1) based on the vacuum vessel outer diameter x (mm). And it is preferable that it exists in the range beyond the value calculated | required by (2) Formula.
y = 11.25x−525 (1)
y = 5.35x-242 (2)
[0044]
In the electrical contact according to the present invention, the diameter y (mm) is a value x (kVA × 10) obtained by multiplying the rated voltage (kV) and the breaking current effective value (kA).^Three) Based on the following formula (3) or less and the value obtained by formula (4) or more.
y = 0.15x + 22 (3)
y = 0.077x + 20 (4)
[0045]
Furthermore, the vacuum valve in the present invention is obtained by the following equation (5) and the value obtained by the following equation (5) based on the outer diameter y (mm) of the vacuum vessel based on the diameter x (mm) of the electrical contact. It is preferable to be within a range that is greater than or equal to the value obtained.
y = 1.26x + 30 (5)
y = 1.26x + 10 (6)
[0046]
The present invention also provides a vacuum valve having a fixed side electrode and a movable side electrode in a vacuum vessel, and the fixed side electrode and the movable side electrode in the vacuum valve are connected to the outside of the vacuum valve. A vacuum circuit breaker comprising an opening / closing means for driving the movable electrode via an insulating rod, wherein the vacuum valve is the vacuum valve described above.
Hereinafter, the present invention will be described specifically by way of examples.
[0047]
[Example 1]
As an example relating to the present invention, an electrical contact member having a composition of 25Cr-75Cu with a refractory metal of Cr and a highly conductive metal of Cu was prepared. The manufacturing method of this electrical contact member is as follows.
[0048]
The Cr powder, which is a refractory metal, is flattened by roller compression set to a predetermined gap size, and the value obtained by dividing the maximum length of the flat surface by the minimum size of the surface perpendicular thereto (hereinafter referred to as the aspect ratio) is 3, Cr flat powder of 10, 30, 40 (comparative example) was produced. As another comparative example, the raw material Cr powder was used as it was, and the aspect ratio was set to 1. Note that the Cr powder used contained 1100 ppm of oxygen, 800 ppm of Al, and 440 ppm of Si.
[0049]
The Cu powder, which is a highly conductive metal, had a particle size of 80 μm or less and 80 μm or more.
Ten kinds of electrical contact members shown in Table 1 were prepared by combining the above Cr flat powder and Cu powder.
[Table 1]

First, Cr flat powder and Cu powder were mixed by a V-type mixer at a weight ratio of 25:75. Next, this mixed powder was filled in a metal mold having a diameter of 60 mm, and press-molded by applying a pressure of 250 MPa on a circular surface having a diameter of 60 mm by a hydraulic press. The size of the molded body was 60 mm in diameter × 12 mm in thickness, and the relative density was 73%. This is 6.7 × 10^-3Heating was performed at 1050 ° C. for 120 minutes in a vacuum of Pa or lower to produce the electrical contact members shown in Table 1. The relative density after sintering heating was 97 to 98% in all cases.
[0050]
FIG. 1 shows an example of the structure of the produced electrical contact member, and is a structure photograph of sample number C (Cr powder aspect ratio: 10, Cu powder particle size: 80 μm or less). A circular surface of the electrical contact member (hereinafter referred to as contact surface) and a cross section perpendicular thereto were observed using an optical microscope.
[0051]
In FIG. 1, (a) is a structure of a plane parallel to the contact surface, and (b) is a structure of a cross section perpendicular to the contact surface. The uneven plane of the Cr particles occupies a relatively large area on the contact surface of (a), and the uneven plane of the Cr particles is oriented substantially parallel to the contact surface in the cross section perpendicular to the contact surface of (b). confirmed. As a result, Cr powder having a flat plate shape tends to be oriented perpendicularly to the pressing direction, and it is proved that the material structure intended by the present invention can be obtained by making the contact surface parallel to the pressing surface. It was.
[0052]
The contact surfaces of the obtained 10 types of electrical contact members and the cross section perpendicular thereto are observed with an optical microscope, and the ratio of Cr particles oriented in the range of ± 40 ° and ± 20 ° with respect to the contact surfaces is obtained. It was. The ratio of Cr particles was calculated by calculating the area of Cr in each angle range by image processing and calculating the weight ratio with respect to all the Cr contained.
[0053]
Table 1 shows the ratio of Cr in each angle range. When the particle size of Cu is 80 μm or more, 90 wt% or more is + 40 ° to −40 when the aspect ratio of Cr powder is 3 to 40 It was confirmed that the film was oriented in the range of °, and 75% by weight or more was oriented in the range of + 20 ° to −20 °.
[0054]
On the other hand, when the particle size of Cu is 80 μm or less, even when the aspect ratio of Cr powder is 40, Cr in the range of + 40 ° to −40 ° is less than 90% by weight, and + 20 ° to −20. It was confirmed that Cr in the range of ° was less than 75% by weight.
From the above, in order to orient the flat Cr powder in the desired direction, it was proved that the particle size of Cu is desirably 80 μm or less.
[0055]
The results of obtaining the ratio of the area occupied by Cr (area occupancy) in the contact surface and the cross section perpendicular to the contact surface of the obtained electrical contact member are shown together in Table 1, and the grain size of Cu is 80 μm or less. In this case, when the aspect ratio of the Cr powder was 3 to 40, it was confirmed that the contact area had an area occupancy of 30% or more and a vertical section of 14 to 25%. However, when the aspect ratio of the Cr powder is 40 (sample number E), the area occupation ratio of Cr on the contact surface is 50% or more, and when used as an electrode, the contact resistance with the counterpart electrode is large. This is not preferable because the energization performance decreases. Therefore, the aspect ratio of Cr powder is desirably 3 to 30.
[0056]
In addition, the above-mentioned tendency is 1 type or 2 types or more in W, Mo, Ta, Nb, Be, Hf, Ir, Pt, Zr, Ti, Te, Si, Rh, and Ru whose refractory metals are other than Cr. It was confirmed that the same was true when the highly conductive metal was Ag or Au other than Cu or an alloy mainly composed of these.
[0057]
[Example 2]
As another example relating to the present invention, five types of electrical contact members were prepared by changing the Cr content from 10 wt% to 45 wt%, with Cr as the refractory metal and Cu as the highly conductive metal. The aspect ratio of Cr powder was 15, and the particle size of Cu powder was 80 μm or less. The manufacturing method of the electrical contact member is the same as that of the first embodiment. The relative density after sintering and heating of the obtained electrical contact member was 97 to 98%.
[0058]
Table 2 shows the proportion of Cr particles oriented in the range of ± 40 ° and ± 20 ° with respect to the contact surface, as well as the composition of the produced electrical contact member, and the Cr area occupation ratio in the cross section perpendicular to the contact surface Indicates.
[Table 2]

In any composition, it was confirmed that 90% by weight or more of Cr was oriented in the range of + 40 ° to −40 °, and 75% by weight or more was oriented in the range of + 20 ° to −20 °. However, with the composition 10Cr—Cu (sample K), the Cr area occupancy of the contact surface is 30% or less and the vertical cross section is 14% or less, thereby achieving the object of the present invention that achieves both breaking performance and high withstand voltage characteristics. It becomes impossible. Further, the composition 45Cr—Cu (sample O) is not preferable because the contact surface is 50% or more, and the energization performance is lowered. Therefore, it was confirmed that the composition of Cr was 15 to 40% by weight and Cu was 60 to 85% by weight.
[0059]
In addition, the above-mentioned tendency is 1 type or 2 types or more in W, Mo, Ta, Nb, Be, Hf, Ir, Pt, Zr, Ti, Te, Si, Rh, and Ru whose refractory metals are other than Cr. It was confirmed that the same was true when the highly conductive metal was Ag or Au other than Cu or an alloy mainly composed of these.
[0060]
[Example 3]
As a third example relating to the present invention, among the electrical contact members produced in Example 1 and Example 2, for sample numbers A to D and L to N, the tensile strength in the direction perpendicular to and parallel to the contact surface And the specific resistance was measured.
[0061]
Table 3 shows the measurement results.
[Table 3]

[0062]
Compared with sample number A using Cr as raw material powder, the tensile strength in the direction perpendicular to the contact surface was 150 MPa or less in all cases, while the tensile strength in the parallel direction showed a value of 150 MPa or more. . Therefore, since the strength in the direction perpendicular to the contact surface is small, it is easy to peel and break when welded to the counterpart electrode, and the welding resistance is improved.
[0063]
Further, no significant anisotropy is observed in the specific resistance. This indicates that, since the electrical characteristics are almost governed by the composition, the conductivity is not directional even when the Cr powder has a flat shape, and the interruption performance can be maintained at the same level as that of the conventional structure.
[0064]
From the above, it was confirmed that the electrical contact member according to the present invention is relatively easily peeled off in the direction perpendicular to the contact surface, and there is no anisotropy in conductivity.
[0065]
[Example 4]
As a fourth embodiment relating to the present invention, an electrode to be applied to a vacuum valve is manufactured using the members of sample numbers A to E and K to O among the electrical contact members manufactured in

Embodiments

1 and 2. did.
[0066]
FIG. 2 shows the structure of the fabricated electrode. In FIG. 2, 1 is an electrical contact, 2 is a spiral groove for applying a driving force to the arc so as not to stagnate, 3 is a stainless steel reinforcing plate, 4 is an electrode rod, and 5 is a brazing material.
The method for producing the electrode is as follows. The electrical contact member produced in Example 1 and Example 2 is processed into a desired shape by machining to obtain the electrical contact 1. The electrode rod 4 is made of oxygen-free copper, and the reinforcing plate 3 is previously machined by SUS304, and the electric contact 1 and the central hole of the reinforcing plate 3 and the convex portion of the electrode rod 4 are connected to the brazing material 5. And the brazing material 5 is placed between the electrical contact 1 and the reinforcing plate 3, and this is 8.2 × 10.^-FourThe electrode shown in FIG. 2 was produced by heating at 980 ° C. for 8 minutes in a vacuum of Pa or lower. This electrode is used for a vacuum valve for a rated voltage of 7.2 kV, a rated current of 600 A, and a rated breaking current of 20 kA.
[0067]
[Example 5]
A vacuum valve on which the electrode produced in Example 4 was mounted was produced. The specifications of the vacuum valve are a rated voltage of 7.2 kV, a rated current of 600 A, and a rated breaking current of 20 kA.
FIG. 3 shows the structure of the vacuum valve according to this embodiment. In FIG. 3, 1a and 1b are fixed-side electrical contacts, movable-side electrical contacts, 3a and 3b are reinforcing plates, 4a and 4b are fixed-side electrode rods and movable-side electrode rods, respectively, and these are respectively fixed-side electrodes 6a, The movable electrode 6b is configured. The movable side electrode 6b is brazed and joined to the movable side holder 12 via a movable side shield 8 that prevents scattering of metal vapor or the like at the time of interruption. These are brazed and sealed to a high vacuum by the fixed side end plate 9a, the movable side end plate 9b, and the insulating cylinder 13, and are connected to the external conductor through the screw portions of the fixed side electrode 6a and the movable side holder 12. A shield 7 is provided on the inner surface of the insulating cylinder 13 to prevent scattering of metal vapor or the like at the time of interruption, and a guide 11 for supporting a sliding portion is provided between the movable side end plate 9b and the movable side holder 12. Provided. A bellows 10 is provided between the movable side shield 8 and the movable side end plate 9b, and the movable side holder 12 is moved up and down while keeping the inside of the vacuum valve in a vacuum, thereby opening and closing the fixed side electrode 6a and the movable side electrode 6b. I can do it. In this example, the vacuum valve shown in FIG. 3 was manufactured using the electrode having the structure shown in FIG. 2 manufactured in Example 4 as the fixed side electrode 6a and the movable side electrode 6b.
[0068]
[Example 6]
Table 4 shows the results of various performance tests conducted by incorporating the vacuum valve produced in Example 5 into a vacuum circuit breaker.
[Table 4]

[0069]
The respective performances in Table 4 are represented by relative comparison with the value of Sample A having the structure of the conventional material using the raw material Cr as 1.
[0070]
In Samples A to E, the blocking performance does not change even if the aspect ratio of the Cr powder changes. This is because there is almost no change in the specific resistance as shown in Table 3. On the other hand, the withstand voltage performance increases as the aspect ratio increases. This is because, as shown in Table 1, the area occupation ratio of Cr on the contact surface is increased. Also, as the aspect ratio increases, the welding resistance performance also increases. This is because the Cr area occupancy is large, and as shown in Table 3, the tensile strength in the direction perpendicular to the contact surface is reduced, and peeling and separation are easy to occur. Because. However, the sample E in which the aspect ratio of the Cr powder is 40 is not preferable because the contact area between the electrodes increases because the Cr area occupation ratio on the contact surface is large, and the energization resistance is large. Therefore, when the aspect ratio of the Cr powder is 3 to 30, it was proved that there is an effect in improving the withstand voltage characteristics and the welding resistance performance while maintaining the interruption performance.
[0071]
In samples K to O, the breaking performance of sample N is 0.9, which is smaller than that of sample A having a conventional structure, but can be applied to a vacuum breaker for a rated breaking current of 20 kA. However, the sample O had insufficient breaking performance and was difficult to apply to a vacuum breaker for a rated breaking current of 20 kA. Further, when the Cr amount is reduced, the withstand voltage performance is lowered, and the breaking performance is lowered due to the reoccurrence of the arch accompanying therewith, and it was difficult to apply the sample K to a vacuum circuit breaker having a rated voltage of 7.2 kV. Accordingly, the Cr content is suitably 15 to 40% by weight.
In addition, about the electrode produced by the method similar to Example 4 using the electrical contact member which put the electric contact member produced in Example 1 and Example 2 into a metal mold again, and was pressurized with 400, 600, and 800 MPa. A similar performance evaluation was performed. Here, the electric contact member pressurized at any pressure had a relative density of 98.5% or more. As a result, the same tendency as the above results was obtained, and the shutoff performance tended to be further stabilized. This is because densification progressed by pressurizing again after sintering, and internal defects and the amount of internal gas decreased.
[0072]
From the above, it has been demonstrated that the electrical contact member according to the present invention is useful for achieving both breaking performance, high withstand voltage characteristics, and welding resistance.
[0073]
[Example 7]
As another manufacturing method relating to the present invention, electrical contact members similar to those in Example 1 and Example 2 were produced. FIG. 4 is a schematic view showing the manufacturing method and manufacturing apparatus of the present embodiment. In FIG. 4, 14 is a container for containing the raw material mixed powder 15, 16 is a molding machine for continuously extruding the raw material mixed powder 15 filled from the container 14, and 17 is the raw material mixed powder 15 while rotating. Roller for molding and feeding, 18 is a formed plate-shaped continuous molded body, 19 is a tunnel furnace for continuously heating and sintering the continuous molded body 18 in an inert atmosphere, and 20 is heated and sintered. The obtained continuous sintered body, 21 is a rolling roller for rolling and densifying the continuous

sintered body

20, 22 is a rolled electrical contact member, and 23 is an electrical contact 24 having a desired shape from the electrical contact member 22. A die 25 for punching out a belt 25 is a belt for continuously conveying and moving the electrical contacts 24 obtained by punching.
[0074]
The molding pressure, sintering temperature, pressure during rolling after sintering, and the like in this example were set so as to be substantially the same as in Example 1 and Example 2.
[0075]
When the structure, tensile strength, specific resistance, and the like of the electrical contact member obtained in this example were examined, results almost the same as those obtained in Example 1 and Example 2 were obtained.
[0076]
Therefore, according to this manufacturing method, it is possible to continuously manufacture a large amount of electrical contact members, which is low in cost and excellent in productivity, and further achieves the object of the present invention that achieves both breaking performance, high withstand voltage characteristics, and welding resistance. It was confirmed that a matching electrical contact member was obtained.
[0077]
[Example 8]
Table 5 shows the specifications of vacuum valves of various ratings prepared using the members of Sample B as electrical contacts 1a and 1b.
[Table 5]

[0078]
FIG. 5 is a diagram illustrating the relationship between the effective value of the breaking voltage current (y) and the outer diameter (x) of the vacuum vessel. The cut-off voltage current effective value is obtained by multiplying the cut-off voltage (kV) by the cut-off current effective value (kA). As shown in FIG. 5, the outer diameter of the vacuum vessel with respect to the effective value of the cut-off voltage current so that the effective value of the cut-off voltage current (y) falls between the values obtained by 11.25x-525 and 5.35x-242. Is preferable.
[0079]
FIG. 6 is a diagram showing the relationship between the electrical contact diameter (y) and the breaking voltage current effective value (x). The electrical contact diameter (y) is preferably set so as to fall between values obtained by 0.15x + 22 and 0.077x + 20 with respect to the breaking voltage current effective value (x).
[0080]
FIG. 7 is a diagram showing the relationship between the vacuum vessel outer diameter (y) and the electrical contact diameter (x). The outer diameter (y) of the vacuum vessel is preferably set between values obtained by 1.26x + 30 and 1.26x + 10. In the present embodiment, it is almost set to a value obtained by y = 1.26x + 19.6.
[0081]
【The invention's effect】
The electrical contact member according to the present invention has a structure in which the refractory metal powder having a flat plate shape is oriented parallel to the contact surface in a matrix made of a highly conductive metal, so that the area occupied by the refractory metal powder on the contact surface is Thus, the high withstand voltage characteristic and the welding resistance can be improved without reducing the breaking performance.
In addition, according to the manufacturing method of the present invention, the electrical contact member having the above material structure can be efficiently mass-produced, so that the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a photograph showing an example of the structure of an electrical contact member according to Example 1 of the present invention.
FIG. 2 shows the structure of an electrode according to Example 4 of the present invention.
FIG. 3 shows the structure of a vacuum valve according to Example 5 of the present invention.
FIG. 4 shows a manufacturing method and a manufacturing apparatus according to Embodiment 7 of the present invention.
FIG. 5 shows the relationship between the effective value of the cutoff voltage current of the vacuum valve and the outer diameter of the vacuum container according to Example 8 of the present invention.
FIG. 6 shows a relationship between a diameter of an electric contact of a vacuum valve according to Example 8 of the present invention and an effective value of breaking voltage current.
FIG. 7 shows the relationship between the outer diameter of a vacuum vessel and the diameter of an electrical contact of a vacuum valve according to Example 8 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electrical contact, 1a ... Fixed side electrical contact, 1b ... Movable side electrical contact, 2 ... Spiral groove, 3, 3a, 3b ... Reinforcement plate, 4 ... Electrode rod, 5 ... Brazing material, 6a ... Fixed side electrode, 6b ... movable side electrode, 7 ... shield, 8 ... movable side shield, 9a ... fixed side end plate, 9b ... movable side end plate, 10 ... bellows, 11 ... guide, 12 ... movable side holder, 13 ... insulating cylinder, 14 ... Container, 15 ... Raw material mixed powder, 16 ... Molding machine, 17 ... Roller, 18 ... Continuous molded body, 19 ... Tunnel furnace, 20 ... Continuous sintered body, 21 ... Rolling roller, 22 ... Electric contact member, 23 ... Mold 24 ... electrical contacts, 25 ... belt.

Claims

The refractory metal powder having a flat plate shape is dispersed in a matrix made of a highly conductive metal, the refractory metal powder has a flat plane oriented in one direction, and the flat surface of the refractory metal powder and An electric contact member characterized in that a parallel surface is used as a contact surface.

2. The electrical contact member according to claim 1, wherein the refractory metal powder having a flat plate shape has a value obtained by dividing the maximum length of the flat plane by the minimum dimension of the plane perpendicular thereto, from 3 to 30.

3. The electricity according to claim 1, wherein 90% by weight or more of the refractory metal powder having a flat plate shape has a flat plane oriented in a range of + 40 ° to −40 ° with respect to the contact surface. Contact member.

In any one of Claims 1-3, the refractory metal powder which has a flat-plate shape is Cr, W, Mo, Ta, Nb, Be, Hf, Ir, Pt, Zr, Ti, Te, Si, Rh, and Ru. An electrical contact member comprising one kind or a mixture of two or more kinds thereof or a compound thereof, wherein the highly conductive metal comprises Cu, Ag, Au, or an alloy mainly composed of these.

4. The electrical contact member according to claim 1, wherein the refractory metal powder having a flat plate shape contains 50 to 2000 ppm of oxygen, 50 to 3000 ppm of Al, and 100 to 2500 ppm of Si.

The electrical contact member according to claim 1, comprising a refractory metal powder having a flat plate shape of 15 to 40% by weight and a highly conductive metal of 60 to 85% by weight.

The area ratio of the refractory metal powder having the flat plate shape on the contact surface is 30 to 50%, and the area ratio of the refractory metal powder having the flat plate shape on the surface perpendicular to the contact surface is 14 to 25%. The electrical contact member according to claim 1, wherein:

The electrical contact member according to claim 1, wherein the refractory metal powder having the flat plate shape has an oxygen content of 2500 ppm or less.

A mixed powder of a refractory metal powder having a flat plate shape and a highly conductive metal powder is pressure-molded at 120 to 500 MPa to produce a molded body, and the molded body is placed in a vacuum or in an inert atmosphere with the above high A method for producing an electrical contact member, characterized in that sintering is performed at a temperature equal to or lower than the melting point of the conductive metal powder, and the contact surface is formed in parallel with the pressing surface in the molding process.

A mixed plate of a refractory metal powder having a flat plate shape and a highly conductive metal powder is produced by extrusion compression molding to produce a continuous plate-like or rod-like molded body, and the molded body is placed in the inert atmosphere in the above-mentioned high A process for producing an electrical contact member, characterized in that it is continuously sintered below the melting point of the conductive metal powder, and a surface parallel to the extrusion direction is used as a contact surface.

The method for producing an electrical contact member according to claim 9 or 10, wherein the particle size of the highly conductive metal powder is 80 µm or less.

A vacuum valve comprising a fixed electrode and a movable electrode in a vacuum vessel, wherein the electric contact member according to claim 1 is used for the fixed electrode and the movable electrode. .

In a vacuum valve provided with a fixed side electrode and a movable side electrode in a vacuum vessel, the both electrodes comprise an electrical contact using the electrical contact member according to claim 1 and an electrode rod connected to the electrical contact, and the vacuum The container is a cylinder, and a value y obtained by multiplying the rated voltage (kV) and the effective breaking current (kA) is equal to or less than a value obtained by the following equation (1) based on the outer diameter x (mm) of the vacuum container. (2) A vacuum valve characterized by being in a range equal to or greater than a value obtained by the equation.
y = 11.25x−525 (1)
y = 5.35x-242 (2)

In the vacuum valve provided with the fixed side electrode and the movable side electrode in the vacuum vessel, the both electrodes are composed of an electrical contact using the electrical contact member according to any one of claims 1 to 8 and an electrode rod connected thereto. The diameter y (mm) of the electrical contact is equal to or less than the value obtained by the following equation (3) based on a value x (kVA × 10 ³ ) obtained by multiplying the rated voltage (kV) and the effective value of the breaking current (kA). And a vacuum valve characterized by being in a range equal to or greater than a value obtained by the equation (4).
y = 0.15x + 22 (3)
y = 0.077x + 20 (4)

In the vacuum valve provided with the fixed side electrode and the movable side electrode in the vacuum vessel, the both electrodes are composed of an electrical contact using the electrical contact member according to any one of claims 1 to 8 and an electrode rod connected thereto. The vacuum vessel is a cylinder, and the outer diameter y (mm) of the vacuum vessel is obtained from the value obtained by the following equation (5) based on the diameter x (mm) of the electrical contact and by the equation (6). A vacuum valve and a vacuum circuit breaker using the same, characterized by being in a range that is greater than or equal to a value to be obtained.
y = 1.26x + 30 (5)
y = 1.26x + 10 (6)

Via a vacuum valve having a fixed side electrode and a movable side electrode in a vacuum vessel, and an insulating rod connected to the outside of the vacuum valve to each of the fixed side electrode and the movable side electrode in the vacuum valve The vacuum circuit breaker provided with the opening-closing means which drives the said movable side electrode, The said vacuum valve consists of a vacuum valve in any one of Claims 13-15, The vacuum circuit breaker characterized by the above-mentioned.